Class II mod amalgum cavity preparation step by step?

## Class II MOD Amalgam Cavity Preparation Step by Step

1. Outline Form

* Begin with a round bur and place a retention groove (RG) in the central fossa and an anti-rotation groove (ARG) in the buccal and lingual sulci.

* Extend to slightly beyond the proximal contacts.

* Next, extend the outline into the proximal box using either:

* A round bur

* An inverted cone bur

* An Endo Z bur

2. Resistance Form

* Remove sufficient enamel to create all walls at 90 degrees to the direction of the anticipated occlusal force.

3. Retention Form

* A dovetail is recommended for this type of cavity.

4. Convenience Form

* Create sufficient access for both instrumentation and restoration

5. Pulp Protection

* Ensure enough dentin is removed to make a layer of cement about 0.5mm thick.

6. Preparation Finish

* With a finishing bur remove any sharp angles from the cavity margins and smooth out any irregularities of the cavity walls.

7. Clean and Isolate the cavity

* Rinse with water and remove debris with an air-water syringe and cotton wool and then isolate with either cotton rolls or rubber dam if necessary.